In the field of endo-photocoagulation laser treatment at the retina during eye surgery, it is desirable to combine more than one function in the same probe. Different designs have been in use to address this issue.
Most often, means for delivering laser and illumination energy to the treatment site are combined via a single cannula. This arrangement is generally advantageous in order to reduce the trauma to the eye (by having one less entry point), to release the doctor's hand from having to manipulate an extra instrument, and to provide better targeting of the treatment site.
As the industry has moved towards smaller cannulas (typically, 25 gauge and 23 gauge, as opposed to the larger, 20 gauge cannula) that hold fiber optics for both laser and illumination, less space is available to accommodate the fiber optics. Accordingly, in smaller cannulas, the design tendency has been to reduce the diameter of the illumination and/or laser fibers, which disadvantageously results in lower efficiency levels.
As the technology has evolved, however, it was found that extending the laser tip beyond the illumination fiber by about 3 mm offers better results, partly by allowing greater illumination area coverage at the treatment site.
Currently, the larger, 20 gauge size has enough space to accommodate the illumination fiber optic, having its tip flush with the probe cannula and, on the side and contained within the same probe cannula, a laser fiber optic that extends about 3 mm beyond the tip of the illumination fiber optic. As the laser fiber optic would have no protection against breakage inside the eye, a tube holds the laser fiber optic and extends into the probe cannula, running parallel with the illumination fiber optic.
Scaling down such a design from 20 gauge to the smaller sizes described above has an adverse effect on the performance of the device. For example, with smaller probe cannulas, protecting the laser fiber optic with a tube consumes valuable area and forces the designer to reduce the illumination fiber diameter to a level that renders it much less capable of delivering enough light to the surgical site.
On the other hand, having a smaller laser fiber optic helps provide more space for the illumination fiber, but poses a new set of challenges for alignment of the laser source with the smaller fiber optic.
Accordingly, it would be advantageous to provide one or more solutions to the aforedescribed problems. Such a solution would deliver an appropriate amount of both illumination and laser energy to a surgical site, and would allow the fiber optic delivery system for both energy sources to be housed within a single cannula of any of the standard sizes. It is to the provision of such solutions that the present disclosure is directed.